"I can pretty much say all of us know when Downton is going to end," Coyle told the Radio Times.

"This is a show with a finite life. If we bring this into the '50s, it's Emmerdale."

Speaking of his own character, who is accused of his wife's murder, he added: "Bates was in the Boer War. He would have killed a lot of people. Does that mean he can kill his wife? What does it do to you?"

Insiders have predicted that Downton Abbey will run for two more series, before drawing to a close when key actors move on to other projects.